The operation, which began April 28, is still going on, Nigerian military spokesman Texas Chukwu told CNN. Those rescued are mainly women and children, as well as some young men who had been forced to become Boko Haram fighters, Chukwu said in a statement. The captives were rescued in Borno state, in northeastern Nigeria, the army said. No further details were given about their identity. "Those rescued are receiving treatment at a military facility," the statement said.The rescue mission follows the release of more than 100 schoolgirls kidnapped in March by Boko Haram from Dapchi, a town in Nigeria's Yobe State.The operation, which was conducted in conjunction with Cameroonian and Nigerian troops of the Multinational Joint Task Force, rescued the hostages from Malamkari, Amchaka, Walasa and Gora villages of the Bama Local Government Area.Boko Haram terror group militants mainly inhabit areas in the northern states of Nigeria, specifically Yobe, Kano, Bauchi, Borno and Kaduna.Boko Haram has kidnapped more than 1,000 children in Nigeria since 2013 according to a new report. The group sparked global outrage after its militants seized 276 girls from a boarding school in Chibok town in Borno state in 2014.Some of those girls were freed last year following negotiations between the Nigerian government and Boko Haram. CNN has not been able to confirm whether the remaining Chibok girls were among those freed in the latest operation.Last month, the Nigerian government said a disagreement between members of the terror group had caused a breakdown in negotiation talks for the release of the remaining schoolgirls.